We have a Windows 2003 server with two network cards and two different gateways. One gateway is set to a T1 line (192.168.10.252) and the second is set to a Comcast line (192.168.1.254). When we enter in both gateways, sometimes people get disconnected randomly while connected through either the T1 or the Comcast line. The server seems to shift randomly between using the T1 gateway for a while, and then switching to the Comcast gateway. If it is using the Comcast gateway, connections to the T1 IP address aren't accepted. Then when the server switches back to using the T1 gateway, no one can connect through the Comcast line.
We need to be able to have this server use the T1 connection when the Comcast line is down. How do we do this using the two network cards present in the system?
Secondly, how do we set up DNS so if users can't connect through the Comcast IP, they are automatically redirected to the T1 IP? And if they can't connect through the T1 IP, redirected to a third IP?